Corn harvesting combines utilize one or more roll or row units positioned in front of the combine with each unit engaging a row of corn stalks as the combine moves forward. Each unit has a pair or set of counter-rotating and cooperating stalk rolls with outwardly extending blades or flutes that grip the corn stalks therebetween and pull the stalks downwardly. The flutes grip and pull the stalk downwardly through the rolls until the ear of corn strikes against plates positioned above and adjacent the stalk rolls, thereby separating the ear from the stalk. If the stalk is severed prior to the ear striking the plates, the stalk and ear will both fall into the combine, which reduces combine capacity. Once the ear strikes the plates and is removed from the stalk, the stalk is pushed downwardly toward the ground by the rolls and dropped in the field to eventually dry out and decompose.
Ideally, the stalks are discarded in the wake of the combine. The discarded stalks may be chopped up before new plowing or seeding can be done. Increased chopping action advantageously provides for faster decomposition, easier tillage and better insect control. Furthermore, residue cover, as typically measured, would increase with the stalk being cut into more pieces. It is desirable, therefore, that the stalk undergo as much breakage and mutilation as possible during combining. Previous rolls have been ineffective in adequately breaking up the stalk residue and the farmer must make repeated passes with disks and shredders to mutilate the stalks in order to prepare the field for plowing.
Since the invention of the corn-harvesting combine, many stalk roll designs have been developed. Most designs only work satisfactorily when the combine moves at slow ground speeds with moderately dry corn and under reasonably dry field and weather conditions. As ground speed is increased the performance of conventional stalk rolls significantly deteriorates with increasing numbers of stalks severed before ear removal.
Furthermore, corn harvesting is often done late in the growing season just before freezing and at a time when the weather is unpredictable at best. Frequently the crop is wet from rain. The muddy field and cool temperatures allow little chance of rapid drying. As a result the farmer must harvest his crop within a short time interval or risk loss or deterioration of the crop due to worsening weather. When time is short, it may be necessary to harvest in the rain and at high speed.
Also, different varieties of corn affect stalk roll performance. For example, moisture content, stalk thickness, ear size, ear placement and fiber consistency of the stalk, may help or hinder stalk roll operation. Specifically, corn crops like sweet corn are harvested when the stalks are still green and contain high levels of moisture. Such stalks are far more prone to slip during stalk engagement than are dry stalks.
Most stalk rolls have a central, one-piece cylindrical steel core and outwardly extending flutes attached thereto. Some designs have plates with bilaterally symmetrical flutes extending from lateral ends thereof, which detachably engage the cylindrical core. This design, while having the benefit of detachable plates, is not considered aggressive under wet crop conditions from either a stalk gripping or a stalk-mutilating standpoint. More specifically, the flutes lack knife-edges and the edges do not overlap. Other more aggressive designs have flutes with knife-edges that are offset to one another and overlap in the shear zone area. This design, however, lacks the benefit of having detachable flutes. Furthermore, although opposing flutes overlap, they are not sufficiently adjacent one another during stalk shear so as to aggressively mutilate the stalk as well as prevent stalk slippage.